The subject matter disclosed herein relates to a system for converting audio signals to wireless audio signals in a medical imaging environment. More specifically, a device may be operatively connected to an existing audio system for a magnetic resonance imaging (MRI) system to receive audio signals generated by the audio system and to convert the audio signals to wireless audio signals for delivery to a wireless headset worn by a patient on the scan table.
As is known to those skilled in the art, a magnetic resonance imaging (MRI) system alternately generates a strong magnetic field and then detects the faint nuclear magnetic resonance (NMR) signals given off by nuclei in the presence of the magnetic field. The NMR signals are received by antennas, also known as coils, and transmitted to the MRI scanner for reconstruction into an MRI image. In order to provide a clear image, it is desirable to minimize interference associated not only with external artifacts, such as electromagnetic interference, but also with motion artifacts, such as voluntary or physiologic motion.
During a MRI procedure, the MRI scanner generates a significant level of audible noise in the scanner's switching gradient coils. The rapid switching of the coils to generate the magnetic field in the scanner causes vibration in the coils. The vibration, in turn, generates audible noise. As the switching speed and strength of the gradient coils in the scanner increase, the magnitude of noise increases as well. The magnitude of noise in an MRI scanner is sufficient that communication with a patient during the MRI procedure becomes difficult. Typically, headsets are provided such that audio signals containing instructions or information from a technician performing the procedure to be delivered directly to the patient's ear. Further, the headsets may include some level of noise protection to reduce the level of ambient noise generated by the MRI scanner from reaching the patient's ear.
The MRI environment creates numerous challenges that make conventional electronic headsets unusable in the MRI environment. Most commercial headsets utilize a magnetic speaker driver and may include one or more other components that are susceptible to magnetic fields. The magnetic field generated by the MRI scanner may, at a minimum, interfere with these devices, and at worst, pull the devices into the bore of the scanner, potentially injuring the patient. Further, non-magnetic metal components may be susceptible to radio frequency (RF) induced heating. Also, long wire runs, for example, between the control room and the patient or even between earphones function as antennas. These long wire runs raise the potential of both radiating electromagnetic interference detectable by the MRI scanner due to audio signals transmitted on the wire and receiving interference from the MRI scanner which degrades the audio signal provided to the patient.
Historically, these limitations of conventional electronic headsets have been overcome by providing pneumatic headsets to the patient. However, such a system is not without drawbacks. The pneumatic headsets require a dedicated controller with a speaker to convert an electronic audio signal to an audile audio signal proximate a first end of a pneumatic tube. The pneumatic tube, in turn, acts as a conduit for transmitting the audible audio signal to the patient. Pneumatic tubing extending from this controller o the patient is also required.
On some scanners, the controller is provided on the scanner or within the scan table. The pneumatic tubing must extend from the controller to the patient. The scan table typically includes a sliding top such that the patient may initially get on the table and be oriented by a technician on the table top external to the MRI scanner. The top then slides into the bore of the MRI scanner to perform the imaging. The pneumatic tubing must be provided with sufficient length to plug into the table and allow the headphones to reach the length of the table and in some instances to also accommodate the travel of the table into and out of the bore of the MRI scanner.
With other scanners, no controller is provided and a separate controller must be provided within the scan room. Pneumatic tubing must be routed between the controller and the scanner. The tubing may be routed along the floor or within troughs embedded in the floor of the scan room. Tubing along the floor presents a trip hazard within the scan room and complicates work flow for other medical equipment that must be positioned within the scan room. Whether routed along the floor or within troughs, the length of the tubing increases if the controller is located remotely from the scanner.
Thus, it would be desirable to provide an improved system for providing the audio signals to the patient.